Conventional faucets have a wide variety of styles and operations. However, if the user forgets to close the faucet handle as a result of drying hands, fails to close it tightly, the faucet has malfunctioned, or the faucet has been opened by a prankster, water flow will continue without stop so as to cause waste. Though the optical sensor type is an improvement which allows the water supply to be stopped as soon as the user leaves or after flushing fr a specific time, it has a higher possibility of failure due to its electronics. Furthermore, it has a high production cost, complex assembly work, additional power consumption by connection to an external power source, and involves a high risk of safety in a wet environment.